(1) Field of the Invention
This invention relates to elastomeric bearings, and more particularly to elastomeric bearings used in helicopter main rotor and tail rotor assemblies.
(2) Description of the Related Art
Snubber/damper units are well known in the field of helicopter rotor technology. Exemplary snubber/damper units are shown in U.S. Pat. Nos. 5,188,513, 5,092,738, 4,244,677, and 4,105,266. An exemplary snubber/damper is used in a bearingless rotor application to accommodate relative movement and orientation changes of an inner blade member to an outer blade or mounting member. In a common implementation, two snubber/damper subunits are mounted on opposite sides of the inner member. The subunits include a spherical stack of bonded metallic shims and elastomeric spacers to accommodate pitch and flap motions and a flat stack to accommodate lead-lag and, if present, longitudinal motions. The spherical stack is commonly identified as the snubber and the flat stack is commonly identified as the damper. In a common configuration, the spherical layers of the two subunits are concentric.